Aluminum halohydrate

ABSTRACT

An aluminum halohydrate is formed by first preparing a reactive aluminum by permeating highly pure aluminum with mercury in the presence of a hydrogen ion source and then contacting the reactive aluminum with a source of iodine, chlorine bromine or fluorine in the presence of water. The products obtained show high stability, uniformity from batch to batch, and a pH of about 4.3.

CROSS REFERENCE TO RELATED APPLICATIONS

This is a continuation-in-part of both of the two co-pending patentapplication Ser. No. 45,527 filed June 11, 1970 now abandoned andapplication Ser. No. 127,351 filed Mar. 23, 1971 now abandoned.Application Ser. No. 45,527 is a continuation-in-part of applicationSer. No. 859,703 filed Sept. 22, 1969. Application Ser. No. 127,351 wasa continuation-in-part of both application Ser. No. 859,703 nowabandoned and the application Ser. No. 45,527.

Reference is made to the following co-pending applications: ReactiveMetals, Ser. No. 211,979 filed Dec. 27, 1971 now abandoned; AluminumHydrates and Salts of Carboxylic Acids, Ser. No. 255,757 filed May 22,1972 now abandoned; Metal Hydrates and Salts of Carboxlic Acids, Ser.No. 255,758 filed May 22, 1972 now abandoned; and Composition of Matterand Apparatus and Method for the Same, Ser. No. 176,907 filed Sept. 1,1971.

BACKGROUND OF THE INVENTION

The present invention relates to methods of forming selected aluminumhalohydrates and to the aluminum halohydrates formed thereby.

The present invention relates more particularly to the methods offorming aluminum iodohydrate, aluminum chlorohydrate, aluminumbromohydrate, and aluminum fluorohydrate.

Generally, aluminum halohydrates have found substantial commercialusages in a wide variety of fields, including use as an activeingredient in body deodorants, tawing salts, and for the impregnation oftextiles to impart water repelling properties. In addition, aluminumhalohydrates are also used for the preparation of absorption agents orcatalytically active substances. Many other commercial uses for thechemicals are well known.

Prior art methods for preparing aluminum halohydrates often include thestep of reacting an aluminum halide salt, such as aluminum fluoride,aluminum chloride, aluminum bromide or aluminum iodide with water andmetallic aluminum. The process described in the U.S. Pat. No. 3,476,509includes the use of a water soluble thallium compound with a pH ofbetween 2.5 and 4.4 at an elevated temperature in the order of 70° C. to105° C. The aluminum hydrate formed from an aluminum halide usuallyshows traces of the aluminum halide. This has been recognized to be avery serious problem especially for aluminum chlorohydrate when used asan antiperspirant because the aluminum chloride hydrolyzes tohydrochloric acid and results in severe skin irritation. The presence ofthe aluminum halide also tends to make the aluminum halohydrateshygroscopic.

The article entitled, "Basic Aluminium Compounds" by Hideo Tanabe in TheAmerican Perfumer and Cosmetics, Vol. 77, August 1962 pages 25-30provides a review of known methods for preparing aluminum halohydrates.On page 26, Tanabe presents four methods by way of equations (5), (6),(7), and (8). The four methods are briefly given herein for reference:

1. More than an equivalent amount of metallic aluminum is reacted withan acid, or metallic aluminum is reacted with an aluminum salt with acatalyst of mercury, iron, or copper;

2. More than an equivalent amount of aluminum hydroxide is reacted withan acid;

3. An alkali is added to an aluminum salt solution; and

4. An aqueous solution of an aluminum halide is passed through an anionexchange resin.

On page 26, Tanabe presents the general formula Al₂ _(+n) OH_(3n) X₆ andindicates that when "n" is large, the solution is slightly turbid butcan be made clear by filtration with carbon powder. Tanabe continueswith an analysis of the aluminum chlorohydrate and states that each ofthe four reactions results in a basic aluminum ion which condensesgradually into a polynuclear ion and this condensation is influenced byvarious conditions such as temperature, time and the the value of "n".Thus, the aluminum chlorohydrate reported by Tanabe appears to showinstability with both temperature and time. An earlier Tanable articlein Pharm. Soc. Japan, 75 page 868 (1955) is directed to the study ofthese instabilities.

Another earlier article by Tanabe, in Pharm. Soc. Japan, 74, page 868(1954) states explicitly that the properties of aluminum chlorohydratevaries with the method of preparation.

SUMMARY OF THE INVENTION

One of the principal objects of the Invention is to provide a method forpreparing aluminum iodohydrate, aluminum chlorohydrate, aluminumbromohydrate and aluminum fluorohydrate by the steps of first permeatingaluminum having a purity by weight of at least 99.98% with mercury inthe presence of a hydrogen ion source, such as an acid, and thencontacting the permeated aluminum with an appropriate halogen ion sourcein the presence of an excess of water compared to the halogen, inaccordance with the formula Al₂ (OH)₅ X where "X" corresponds to theselected halogen.

Another object of the present invention is to obtain novel aluminumiodohydrate, aluminum chlorohydrate, aluminum bromohydrate and aluminumfluorohydrate compounds exhibiting novel properties.

A further object of the present invention is a method of preparingselected aluminum halohydrates having a desired ratio between thealuminum and halogen atoms.

Yet another object of the present invention is to provide a method forpreparing aluminum iodohydrate, aluminum chlorohydrate, and aluminumbromohydrate by the use of the corresponding gas in the presence ofwater.

Yet another object of the present invention is a method for preparingaluminum iodohydrate from iodine crystals in water.

Further objects and advantages of the invention will be set forth inpart in the following specification and in part will be obvioustherefrom without being specifically referred to, the same beingrealized and attained as pointed out in the claims hereof.

The present invention accordingly comprises the several steps and therelation of one or more of such steps with respect to each of theothers, all as exemplified in the following detailed disclosure, and thescope of the application of which will be indicated in the claims.Furthermore, the products obtained are novel and exhibit propertieswhich are superior to known corresponding products. For example, theproducts obtained are water-clear when dried to a solid, are soluble inwater, and are not hygroscopic. In addition, the aluminum iodohydrate,aluminum chlorohydrate, and aluminum bromohydrate exhibit superiorbacterialcidal properties.

BRIEF DESCRIPTION OF THE DRAWINGS

For a fuller understanding of the nature and object of the invention,reference should be had to the following detailed description, taken inconnection with the accompanying drawings, in which:

FIG. 1 is an infrared spectra response for aluminum iodohydrate preparedaccording to the present invention;

FIG. 2 is an infrared spectra response for aluminum chlorohydrateprepared according to the present invention;

FIG. 3 is an infrared spectra response for an aluminum bromohydrateprepared according to the present invention; and

FIG. 4 is an infrared spectra response for an aluminum fluorohydrateprepared according to the present invention.

THE INVENTION

The present invention is focused on the utilization of the remarkableproperties of a reactive aluminum described in application Ser. No.211,979, now abandoned.

Generally, a reactive aluminum is prepared by permeating highly purealuminum in the presence of a hydrogen ion source with mercury. Thehydrogen ion source can be an inorganic acid, such as hydrochloric acidor hydrobromic acid or the like, or an organic acid, such as citric acidor acetic acid, or the like. The reactive aluminum in an alkali solutionsuch as water and sodium hydroxide will serve as an hydrogen ions sourcefor the formation of another reactive aluminum.

It should be understood that the term "highly pure" herein means apurity greater than 99.98% by weight.

The concentration of the acid employed can cover the broadest range. Thechoice of the hydrogen ion source such as an acid will depend upon theproduct to be formed and the concern over impurities.

It is preferable to prepare a highly pure aluminum rod for the reactionby at least partially stripping the aluminum oxide coating which usuallyhas formed on the surface due to exposure to air and moisture. Ofcourse, other than a rod shape can be used. If the aluminum rod has beenstripped, hot water can serve as a hydrogen ion source, although thereaction time is long. Otherwise, it may be desirable to start out withan acid to strip off the oxide coating on the aluminum rod in order toinitiate the reaction as quickly as possible. Of course, the aluminumrod may be stripped mechanically with sandpaper or a file or the like.

The inter-reaction which occurs between the aluminum, the mercury andthe acid, gives rise, at the start, to the formation of large bubbleswhich rise up to the surface through the acid. After a while, it will beobserved that instead of large bubbles forming at the top of thealuminum rod and then breaking free and rising to the surface of theacid, tiny bubbles will be eminating from many parts of the uppersurface of the rod. The occurrence of the multitude of tiny bubblesindicates that the rod is becoming converted to reactive aluminum asherein used.

Generally, the rod will take up or absorb from 0.1% to 5% by weight ofthe mercury depending upon the length of time the reaction is permittedto continue. A range of 2% to 3% by weight of the mercury issatisfactory for many applicantion. The maximum mercury content is about5% by weight.

The reaction can be stopped on the one hand due to increase in weight ofthe rod due to the absorption of the metal or on the other hand due tothe production of a multitude of tiny bubbles for a period of 10 to 15minutes. Another basis is to test the rod by immersing it in waterhydrolysis of the water to observe.

A reactive aluminum as described, displays surprisingly active catalyticproperties not at all suggested by the prior art. The reactive aluminumpossesses an altered physical structure and my be used as an activatoror initiator. After grain alingment, the reactive aluminum becomes anopen matrix where the boundaries have expanded.

The amount of the mercury in the aluminum can be varied in accordancewith applications. In general, if a high percent of the mercury byweight is desired, quick cooling of the reactive aluminum afterformation will prevent the squeezing out of the mercury due to anexothermic reaction and lattice expansion. Water or alcohol isconvenient for this purpose. In cases where it is desired to reduce theamount of, mercury from several percent by weight to 0.1% by weight, forexample the reactive aluminum can be heated to squeeze out the mercury.

Certain impurities such as copper and iron, inhibit the formation of areactive aluminum and so should be avoided in the aluminum. Some of theimpurities which inhibit or promote the reaction are given in theaforementioned Reactive Metals application. But, small amounts of theinhibitors can be tolerated for certain applications.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

For a fuller understanding of the invention, certain embodiments havebeen selected for more detailed description.

Generally, a reactive aluminum is reacted with water and a selectedsource of chlorine, bromine, iodine or fluorine. In many cases, it isconvenient to use an acid form of the selected halogen. Sometimes, it isconvenient to use a gaseous form of the selected halogen, such aschlorine gas, bromine gas or iodine vapors. A further possibility is theuse of ground iodine crystals in water.

Basically, the amount of water present compared to the available halogenatoms can be determined from the formula: Al₂ (OH)₅ Q; Q corresponds tothe halogen: chlorine, bromine, iodine of fluorine. It is preferable touse more water than the stoichiometric equivalent of the formula inorder to be assured of having sufficient hydroxyl groups available.

The ratio of the aluminum atoms to the halogen atoms varies from theratio of 2:1. It is highly significant that the ratio of 2.2:1 foraluminum chlorohydrate and 2.4:1 for aluminum bromohydrate can beobtained by the present invention. Also, a ratio of 2.7:1 for aluminumiodohydrate has been obtained by the present methods. Surprisingly, theproduct obtained by the present methods even for high ratios of aluminumto halogen is water clear.

In addition, the products obtained by the present methods show a stablepH of about 4.2 to about 4.3 in contrast to products obtained by priorart methods which have a pH of approximately 3.9.

In carrying out the present methods, it is desirable to cool thereaction to below 100° F. in order to avoid the incidental formation ofan aluminum halide. The presence of an aluminum halide in prior artproducts is considered highly undesirable. However products obtained bythe present methods are non-hydroscopic and are therefore far moresuitable for many applications where prior art products were unsuitable.For example, the present aluminum chlorohydrate is well suited use as anunderarm deodorant even in for high concentrations, since the absence ofaluminum chloride avoids the formation of hydrochloric acid andirritation to human skin. Tests with even relatively concentratedsolutions have verified this for human use.

Another significant advantage of the present product is that the presentproducts become micronized after spray drying and at least 99% will passa 325 mesh. Prior art products require additional treatment in order tobecome micronized after spray drying. This may be related to the factthat prior art products have at least 14% moisture content after spraydrying in contrast to the present products which have only about an 8%moisture content after spray drying.

The aluminum used in the present method preferably is high purityaluminum having a purity of 99.99% by weight and is readily available inrod form but, of course, other shapes can be used. It is preferable toprepare the reactive aluminum with the halogen acid corresponding to thealuminum halohydrate to be formed in order to maintain high purity.Repeated washing of a reactive aluminum can be used for cleansing thereactive aluminum of potential impurities. Usually, it is highlydesirable to form the aluminum halohydrate with a high degree ofassurance that no mercury will appear in the product. This can easily beachieved by using a reactive aluminum having a mercury content by weightsuch that the mercury by weight in the initial reactive aluminumcorresponds to less than approximately 3% by weight of the reactivealuminum after completion of the reaction. It is known that the reactivealuminum retains mercury up to the approximate saturation point of about5% by weight. Thus, calculations can show the amount of aluminum whichwill be consumed to obtain the desired aluminum to halogen ratio for theavailable halogen and these calculations can guide the selection of thetotal weight of the reactive aluminum used and the mercury contentthereof. This is another surprising feature contributing to the highpurity of the product obtained by the present methods.

The aluminum iodohydrate, aluminum bromohydrate, and aluminumchlorohydrate prepared by the present methods exhibit surprisingly goodanti-microbial properties. Standard tests are used to determine theanti-microbial number, namely the concentration to completely destroypseudomonas and aeruginosia in 10 minutes but not 5 minutes. Thealuminum iodohydrate was effective at dilutions in the order of 1000:1to 600:1 and the aluminum chlorohydrate was effective at a dilution inthe order of 1000:1. The Aluminum bromohydrate was effective at adilution of approximately 100:1. The aluminum iodohydrate showedsurprisingly superior anti-microbial activity even compared to IOPREP(trademark), a well known pre-surgical antiseptic. The antimicrobialdilution of the aluminum iodohydrate against staphylococcus andpseudomonas was 400:1 in each case as compared to the IOPREP which was100:1 in each case. Furthermore, one part of a 25% concentrationaluminum iodohydrate was combined with 4 parts of Ivory (trademark) soapand was found effective against staphylococcus even after being diluted80 times. The solution was also effective against pseudomonas but onlyfor a dilution of 40 times.

Therefore, a further step in the present invention includes usingaluminum iodohydrate prepared in accordance for its anti-microbialproperties.

With regard to unusual properties, it is noted that the aluminumbromohydrate is suprisingly well suited for fireproofing such things aswood, clothes and paper. The fireproofing properties can be impartedeither by spraying a solution of the aluminum bromohydrate on the objector soaking the object therein. Naturally, other methods may be use.

After preparing an aluminum halohydrate according to the presentmethods, it may be desirable to enrich the hydroxyl content of thealuminum halohydrate. The enrichment of the hydroxyl content may becarried out by utilizing the product obtained as described inapplicant's co-pending patent application Ser. No. 176,907. Briefly, theproduct of application Ser. No. 176,907 is obtained by placing highlypure aluminum in contact with mercury and an acid with a part of thealuminum exposed to air. The aluminum can be in the form of a rod withthe mercury covering about half of the rod lying therein. A novelproduct forms on the aluminum exposed to the air. The temperature of therod should preferably be maintained below 105° F. Cooling can beaccomplished many different ways but one convenient way is to contactthe aluminum with a large pool of mercury and use only a small amount ofacid to just bearly cover the mercury. The mercury helps to conduct heataway from the rod and therefore cools the rod. An operating temperatureof about 90° F. is preferable. The novel product obtained is extermelyrich in hydroxyl groups and can be added to the aluminum halohydrate andmixed with or without heating to obtain a hydroxyl enriched aluminumhalohydrate.

Sometimes it is desirable to obtain an aluminum halohydrate involving atleast two different halogen atoms. This can be easily accomplished bythe present methods by using, for example, two different acids such ashydrochloric acid and hydrobromic acid. Other variations include, forexample, hydrofluoric acid with chlorine gas pumped therethrough in thepresence of an immersed reactive aluminum.

The products obtained by the present method are polymeric in nature andthe above noted formula should not be considered restrictive because thenumber of aluminum atoms in a unit may exceed the number two and caneasily be 4 or 6 with a corresponding increase, but not necessarilyproportional, number of hydroxyl and halogen atoms included.Furthermore, with regard to the formula, the hydroxyl content could beless then "5" depending upon the available quantity of hydroxyl groups.

Sometimes an alcohol soluble product is desired. Such a product can beobtained by the use of water and alcohol but some instabilities overextended periods of time have been noted for aluminum chlorohydrate.

EXAMPLES

Illustrative non-limiting examples of the practice of the invention areset forth below. Numerous other examples can readily be evolved in thelight of the guiding principles and teachings contained herein. Theexamples are intended merely to illustrate the invention and not in anysense to limit the manner in which the invention can be practiced. Theparts and percentages recited herein and all through this specification,unless specifically provided otherwise, refer to parts by weight andpercentages by weight.

EXAMPLE 1

The procedure for preparing an aluminum chlorohydrate illustrates somegeneral rules. Typically, it is convenient to use a mass of aluminumequal to that needed to obtain a desired ratio. The aluminumchlorohydrate is prepared by first forming a mercury treated reactivealuminum rod and then reacting the reactive aluminum with hydrochloricacid. A rod of 54 grams of aluminum having a purity of 99.98% by weightis permeated in the presence of hydrochloric acid with mercury so thatthe permeated mercury is between 1% to 3% by weight of the rod. Then,the reactive aluminum is immersed in 87 grams of 1.5N hydrochloric acid.Generally, the acid can range between 0.5N and 2N or higher. It ispreferable to maintain the temperature of the reaction below about 100°F. in order to avoid the possibility of forming aluminum chloride or aproduct which does exhibit a stable chemical property. Generally, atemperature of 200° F. or higher should be avoided so that halides arenot formed.

EXAMPLE 2

The reactive aluminum rod of Example 1 is immersed in a solution of 126grams of approximately 38% concentration hydrochloric acid and 300 gramsof water. Again, the reaction temperature is maintained below 100° F.After approximately 72 hours, the liquor contains about 50% by weightsolid aluminum chlorohydrate with the balance being water. The aluminumto chlorine ratio is approximately 2.04:1.

EXAMPLE 3

The reactive aluminum rod of Example 1 is immersed in 250 grams of 50%by weight methanol with the balance being water; then, 36 grams ofchlorine gas is bubbled therethrough over a period of approximately 24hours. The product obtained had an aluminum to chlorine ratio ofapproximately 1.86:1.

EXAMPLE 4

The reactive aluminum of Example 1 is immersed in 87 grams of 38% byweight concentration of hydrochloric acid mixed with 150 grams ofmethanol and 300 grams of water. The temperature is maintained below100° F. by cooling. After 72 hours, the liquor contained approximately50% by weight aluminum chlorohydrate with the balance being mainlymethanol. The aluminum to chlorine ratio was approximately 1.92:1. Whenthe liquor was permitted to dry, alcohol soluble crystals were obtained.

EXAMPLE 5

An aluminum chlorohydrate is prepared with the reactive aluminum ofExample 1 is immersed in 250 grams of water which has been twicedistilled and then chlorine gas is bubbled through the water, preferablyso that the bubbles collide with the reactive aluminum. It may bedesirable to recirculate the gas which has not been reacted. 36 grams ofchlorine reacted over a period of approximately 72 hours producing aliquor having 46% by weight of aluminum chlorohydrate. A reactivealuminum of 59 grams yields a product with a ratio of aluminum tochlorine 2.2:1.

EXAMPLE 6

An aluminum iodohydrate is prepared by using 59 grams of the reactivealuminum of Example 1 in 435 grams of water and 127 grams of powderediodine. The water and iodine are agitated so that the iodine contactsthe reactive aluminum. A product with an aluminum to iodine ratio of2.7:1 is obtained.

EXAMPLE 7

An aluminum bromohydrate is prepared by immersing a 64 gram reactivealuminum in 600 grams of water and introducing 80 grams of bromine gasinto the water so that the bubbles contact the reactive aluminum. Thegas flow should be regulated to occur over a period of several days. Aproduct with an aluminum to bromine ratio of 2.4:1 is obtained.

EXAMPLE 8

An aluminum bromohydrate is prepared by immersing 59 grams a reactivealuminum in 307 grams of water and 162 grams of hydrobromic acid andcontinuing the reaction until an aluminum to bromine ratio of 2.0:1 isobtained. It is preferable to provide cooling.

EXAMPLE 9

An aluminum fluorohydrate is prepared by immersing a reactive aluminumof 54 grams in 307 grams of water and 40 grams of hydrofluoric acid andproviding cooling. A teflon lined reactor is preferable.

EXAMPLE 10

A stable hydroxyl augmented aluminum chlorohydrate is formed by taking150 grams of the aluminum chlorohydrate of Example 1 and combining itwith 40 grams of the oxygen-bearing aluminum complex of application Ser.No. 176,907 and 40 grams of methanol. After the mixture is heated toapproximately 200° F. a stable product is obtained. This product issoluble in alcohol.

EXAMPLE 11

An hydroxyl augmented aluminum chlorohydrate is obtained by adding to150 grams of the aluminum chlorohydrate of Example 1 40 grams of theaforementioned oxygen-bearing aluminum complex, which is an aluminumcomplex including hydroperoxy groups. After mixing, the combination isleft for 24 hours. Then, 10 grams of ethanol are added to the liquor anda reactive aluminum is immersed therein for between 12 to 24 hours. Theresulting product is an aluminum oxychlorohydrate which is soluble inalcohol.

EXAMPLE 12

Example 11 is repeated except that no reactive aluminum is used afterthe ethanol has been added.

When the procedure of any of Examples 1 to 12 is repeated for analuminum having a purity of at least 99.99% a purer product having asuperior quality and preferable for pharmecutical and like applicationsis obtained.

Examples 1 to 12 will result in elemental mercury at the bottom of thereactor. This mercury can be easily avoided by standard techniques forrecovery the desired product. But, some mercury may be held in theliquor obtained and may be highly undesirable. A further step can beused to purge the mercury from the liquor. The purging can beaccomplished by using a reactive aluminum having 500 to 2000 parts permillion. Such a reactive aluminum accumulates and holds mercury so thatthe liquor purity is remarkably improved.

Having thus described the invention, what I claim as new and desire tobe secured by Letters Patent, is as follows:
 1. A method of preparing apolymeric aluminum halohydrate having a ratio of aluminum to halogenatoms of from 2:1 to 2.7:1 and a stable pH of about 4.2 to about 4.3which comprises:reacting an aqueous solution of a halogen acid selectedfrom hydrochloric acid, hydrobromic acid, hydroiodic acid andhydrofluoric acid with mercury permeated aluminum of a purity of atleast 99.98% by weight, the mercury content of said mercury permeatedaluminum ranging from about 0.1 to about 5.0 percent by weight;andcollecting the formed aluminum halohydrate.
 2. The method of claim 1,wherein said mercury permeated aluminum has a mercury content rangingfrom about 2 percent to about 3 percent by weight.
 3. The method ofclaim 1, wherein said aluminum has a purity of at least 99.99 percent.4. The method of claim 1, wherein the reaction is carried out at atemperature below 100° F.
 5. The method of claim 1, wherein thecollected aluminum halohydrate is spray dried.
 6. The method of claim 1,wherein said mercury permeated aluminum is prepared by permeatingaluminum in the presence of a hydrogen ion source with mercury.